Methods and apparatuses for CDMA2000/GPRS roaming

ABSTRACT

IIF architectures and corresponding call flows are provided for CDMA2000/GPRS roaming scenarios such as GPRS foreign mode with Mobile IPv4, GPRS foreign mode with Simple IPv4 or IPv6, CDMA2000 packet data foreign mode with Mobile IPv4, and CDMA2000 packet data foreign mode with Simple IPv4 or IPv6.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present application for patent is a continuation of application Ser.No. 10/996,425 filed Nov. 23, 2004 entitled “METHODS AND APPARATUSES FORDCMA2000/GPRS ROAMING,” issued as U.S. Pat. No. 7,675,885, whichapplication claims priority to Provisional Application No. 60/526,557entitled “CDMA/GPRS Packet Data Roaming” filed Dec. 3, 2003, andassigned to the assignee hereof and hereby expressly incorporated byreference herein.

BACKGROUND

1. Field

The present disclosed embodiments relate generally to wirelesscommunications, and more specifically to roaming in the context ofCDMA2000 and GPRS systems.

2. Background

Wireless subscribers may desire to use their wireless terminals inconjunction with wireless systems other than their home systems toobtain access to services using their existing subscriptions. Access tothese services may be independent of their normal wireless terminals,through wireless systems other than their home systems. This may occur,for example, when the subscriber is roaming outside the service area oftheir home system. Accordingly, manufacturers and system operatorsdesire to allow subscribers to receive services using their terminalsand subscriptions via a system which may not be the subscriber's homesystem, provided that the terminal and the serving system arecompatible.

Serving roaming subscribers can be difficult even when the servingsystem and home system employ identical technologies. When the servingsystem uses an air interface that differs from that used in thesubscriber's home system, interworking between these systems istypically performed due to fundamental differences in message protocols,call models, et cetra. This interworking can be achieved via anInterworking and Interoperability Function (IIF).

One example of an IIF is described in US Patent Application 2002/094811A1 to Bright et al. entitled “Interworking and Interoperability of GPRSSystems With Systems of Other Technology Families.” US PatentApplication 2002/094811 A1 provides a GPRS interworking andinteroperability function (IIF) interposed between a serving GSM/GPRSwireless system and a second wireless system of a different technologyfamily. The IIF allows a mobile station homed to the second wirelesssystem to operate in the GSM/GPRS system. According to US PatentApplication 2002/094811 A1, telecommunications system components areprovided that allow interworking and interoperability of a serving GSMand/or GPRS system with certain “domestic wireless” systems. Forexample, a mobile station homed on such a domestic wireless system, butregistered with the serving system in a GPRS-only mode, may receiveservices from the serving system. US Patent Application 2002/094811 A1mentions that the term “domestic wireless” (DW) is intended to refer tonon-GSM systems compatible with ANSI or equivalent standards for TDMA,CDMA, and analog cellular systems, as generally used in North America,or compatible with other similar systems.

Although US Patent Application 2002/094811 A1 acknowledges the need foran IIF allows a mobile station homed to a CDMA wireless system tooperate in the GSM/GPRS system, US Patent Application 2002/094811 A1does not discuss an IIF adapted for CDMA2000/GPRS roaming scenarios whenthe terminal is using Mobile IP or Simple IP. US Patent Application2002/094811 A1 fails to provide sufficient information, direction orguidance regarding how an IIF could be constructed that would allow amobile station homed to a CDMA2000 wireless system could operate in theGSM/GPRS system, when the terminal is using Mobile IP or Simple IP. Forexample, US Patent Application 2002/094811 A1 fails to provide anydetails regarding what modules would be needed to implement such an IIF,how the modules would be interconnected, timed and controlled so as toobtain the specific operations needed to implement such an IIF.

Thus, there is a need in the art for a general architecture can beadapted for CDMA2000/GPRS roaming scenarios, such as, GPRS foreign modewith Mobile IPv4, GPRS foreign mode with Simple IPv4 or IPv6, CDMA2000packet data foreign mode with Mobile IPv4, and CDMA2000 packet dataforeign mode with Simple IP, Mobile IPv4 or Mobile IPv6. It would bedesirable to enable communication between a CDMA 2000 packet data systemand a GPRS system, when a CDMA 2000 packet data native subscriber usingSimple IP, Mobile IPv4 or Mobile IPv6 roams to the GPRS system bysupporting bearer connectivity between the GPRS and CDMA 2000 packetdata system. Similarly, it would also be desirable to enablecommunication between a GPRS system and a CDMA 2000 packet data systemwhen a GPRS native subscriber roams from the GPRS system to the CDMA2000 packet data system using Simple IP, Mobile IPv4 or Mobile IPv6 bysupporting bearer connectivity between the GPRS system and the CDMA 2000packet data system.

SUMMARY

According to one aspect of the invention, an interface entity,interposed between a CDMA 2000 packet data system and a GPRS system, isprovided that enables communication between the CDMA 2000 packet datasystem and the GPRS system when a CDMA 2000 packet data nativesubscriber roams to the GPRS system by supporting bearer connectivitybetween the GPRS and CDMA 2000 packet data system by providing a packetrouting function.

According to one aspect of the invention, an interface entity isprovided that enables communication between a home CDMA 2000 packet datasystem and a visited GPRS system comprising a SGSN, when a CDMA 2000packet data native subscriber using Mobile IPv4 roams to a visited GPRSsystem.

For example, in an embodiment where a CDMA 2000 packet data nativesubscriber roams to a visited system and uses Mobile IPv4, an interfaceentity can be provided that couples the home system to the visitedsystem to enable communication between the home system and the visitedsystem. In this situation, the home system is a CDMA 2000 packet datasystem that can include a ANSI-41 home location register; an AAA entity;and a home agent, whereas the visited system can be a GPRS system thatincludes a SGSN.

According to one aspect of this embodiment, the interface comprises aGSM home location register emulation module, and an ANSI-41 visitedlocation register emulation module. The GSM home location registeremulation module can be coupled to the SGSN via a Gr interface, thatallows a subscriber to register over a Gr interface, whereas the ANSI-41visited location register emulation module can be coupled to the ANSI-41home location register via a D interface that allows a subscriber toregister over the D interface. According to one aspect of thisembodiment, the interface further comprises a foreign agent emulationmodule and a GGSN emulation module. The foreign agent emulation modulecan be coupled to the home agent via an X1 interface, and supportsbearer connectivity between the visited system and the home system suchthat a foreign agent interface and an AAA interface are presented to theCDMA 2000 packet data system over the X1 interface. The GGSN emulationmodule can be coupled to the SGSN via a Gp interface, and can supportbearer connectivity between the visited system and the home system suchthat a GGSN interface is presented to the visited system over the Gpinterface. The interface can serve as an endpoint for a GTP tunnel and aMobile IP tunnel. In this embodiment, the interface provides a packetrouting function between the GGSN interface and the foreign agentinterface. According to another aspect of this embodiment, the interfacecan also include an AAA emulation module that can be coupled to the AAAentity via an X3 interface. In this embodiment, the AAA emulation moduleprovides an accounting function to interacting with a home network's AAAfor Mobile IP Foreign Agent challenge authentication and 3GPP2 packetdata accounting.

According to one aspect of the invention, an interface entity isprovided that enables communication between a home CDMA 2000 packet datasystem and a visited GPRS system comprising a SGSN, when a CDMA 2000packet data native subscriber using Simple IP roams to a visited GPRSsystem.

In an embodiment where a CDMA 2000 packet data native subscriber roamsto a visited system and uses Simple IP, an interface entity can beprovided that couples the home system to the visited system to enablecommunication between the home system and the visited system. In thissituation, the home system is a CDMA 2000 packet data system that caninclude a ANSI-41 home location register; an AAA entity; and a LNS,whereas the visited system can be a GPRS system that includes a SGSN.

According to one aspect of this embodiment, the interface comprises anANSI-41 visited location register, and a GSM home location register. TheANSI-41 visited location register can be coupled to the ANSI-41 homelocation register via a D interface, and allows a subscriber to registerover the D interface. The GSM home location register can be coupled tothe SGSN via a Gr interface and allows a subscriber to register over theGr interface. According to another aspect of this embodiment, theinterface may comprise a LAC emulation module and a GGSN emulationmodule. The LAC emulation module can be coupled to the LNS via an X2interface, and supports bearer connectivity between the visited and homenetworks over the X2 interface. The GGSN emulation module can be coupledto the SGSN via a Gp interface, and supports bearer connectivity betweenthe visited and home networks over the Gp interface by presenting a GGSNinterface to the visited system and presenting a normal routinginterface to the CDMA 2000 packet data system to thereby provide apacket routing function between the GGSN interface and the home system.In this case, the interface serves as an endpoint for a GTP tunnel andan IPSec tunnel. According to yet another aspect of this embodiment, theinterface can include an AAA emulation module that can be coupled to theAAA entity via an X3 interface. The AAA emulation module can provide anaccounting function by interacting with the home network's AAA for L2TPauthentication and 3GPP2 packet data accounting over the X3 interface.

According to another aspect of the invention, an interface entity,interposed between a GPRS system to a CDMA 2000 packet data system, isprovided that enables communication between the GPRS system and the CDMA2000 packet data system when a GPRS native subscriber roams from theGPRS system to a CDMA 2000 packet data system using one of Mobile IPv4and Simple IP by supporting bearer connectivity between the GPRS systemand the CDMA 2000 packet data system by providing a packet routingfunction.

According to yet another aspect of the invention, an interface entity isprovided that enables communication between a home GPRS systemcomprising a GSM home location register, a GGSN, and an AAA entity, anda visited CDMA 2000 packet data system that comprises an ANSI-41 visitedlocation register, an AAA entity, and a packet data serving node/foreignagent, when a GPRS native subscriber using Mobile IPv4 roams to thevisited CDMA 2000 packet data system.

In an embodiment where a GPRS native subscriber roams to a visitedsystem and uses Mobile IPv4, an interface entity can be provided thatcouples the home system to the visited system to enable communicationbetween the home system and the visited system. In this situation, thehome system is a GPRS system comprising a GSM home location register; aGGSN; and an AAA entity, whereas the visited system can comprise a CDMA2000 packet data system that includes a ANSI-41 visited locationregister; a AAA entity; and a packet data serving node/foreign agent.

According to one aspect of this embodiment, the interface comprises ahome agent emulation module and a SGSN emulation module. The home agentemulation module can be coupled to the packet data serving node/foreignagent via an X1 interface, and presents a home agent interface to thevisited system. The SGSN emulation module can be coupled to the GGSN viaa Gp interface, and presents a SGSN interface to the home system tosupport bearer connectivity between the visited and home networks byproviding a packet routing function between the SGSN interface and thehome agent interface. Here, the interface serves as an endpoint for aGTP tunnel and a Mobile IP tunnel. According to another aspect of thisembodiment, the interface can also include an ANSI-41 home locationregister emulation module, and a GSM visited location register emulationmodule. The ANSI-41 home location register emulation module can becoupled to the ANSI-41 visited location register via a D interface,whereas the GSM visited location register emulation module can becoupled to the GSM home location register via a D interface, to allow asubscriber to register. According to yet another aspect of thisembodiment, the interface may also include an AAA emulation module thatcan be coupled to the AAA entity via a Gi interface and coupled to theAAA entity via a X3 interface. The AAA emulation module interacts withthe visited network's AAA for Mobile IP authentication and 3GPP2 packetdata accounting, over the X3 interface, and the home network's AAA for3GPP packet data accounting, over the Gi interface.

According to one aspect of the invention, an interface entity isprovided that enables communication between a home GPRS systemcomprising a GSM home location register, a GGSN, and an AAA entity, anda visited CDMA 2000 packet data system that comprises an ANSI-41 visitedlocation register, an AAA entity, and a packet data serving node/LACentity, when a GPRS native subscriber using Simple IP roams to thevisited CDMA 2000 packet data system.

In an embodiment where a GPRS native subscriber roams to a visitedsystem and uses Simple IP, an interface entity can be provided thatcouples the home system to the visited system to enable communicationbetween the home system and the visited system. In this situation, thehome system is a GPRS system comprising a GSM home location register; aGGSN; and an AAA entity, whereas the visited system can comprise a CDMA2000 packet data system that includes a ANSI-41 visited locationregister; a AAA entity; and a packet data serving node/LAC entity.According to one aspect of the invention, the interface supports bearerconnectivity between the visited and home networks by providing a packetrouting function. For example, the interface can include a SGSNemulation module, and a LNS emulation module. The SGSN emulation modulecan be coupled to the GGSN over a Gp interface, and presents a SGSNinterface to the home system, whereas the LNS emulation module can becoupled to the packet data serving node/LAC entity over an X2 interface,and presents a L2TP Network Server (LNS) interface to the visitedsystem. As such, this interface provides the packet routing functionbetween the SGSN emulation module and the LNS emulation module. Here,the interface serves as an endpoint for a GTP tunnel and a Mobile L2TPtunnel.

According to another aspect of this embodiment, the interface comprisesa ANSI-41 home location register emulation module and a GSM visitedlocation register emulation module. The ANSI-41 home location registeremulation module can be coupled to the ANSI-41 visited location registervia a D interface, whereas the GSM visited location register emulationmodule can be coupled to the GSM home location register via another Dinterface. This allows a subscriber to register. According to yetanother aspect of this embodiment, the interface may also include an AAAemulation module that can be coupled to the AAA entity via a Y3interface and coupled to the AAA entity via a X3 interface. The AAAemulation module interacts with the visited network's AAA entity, overan X3 interface, for L2TP authentication and 3GPP2 packet dataaccounting, and with the home network's AAA entity, over an Giinterface, for 3GPP packet data accounting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system that comprises a home system, avisited system, and an interface entity that enables communicationbetween the home system and the visited system;

FIG. 2A is a block diagram of GPRS foreign mode with Mobile IPv4;

FIG. 2B is a call flow diagram that shows Mobile IPv4 operation in theGPRS foreign mode;

FIG. 3A is a block diagram of GPRS foreign mode with Simple IP;

FIG. 3B is a call flow diagram that shows Simple IP operation in theGPRS foreign mode;

FIG. 4A is a block diagram of CDMA2000 packet data foreign mode withMobile IPv4;

FIG. 4B is a call flow diagram that shows Mobile IPv4 operation in theCDMA2000 packet data foreign mode;

FIG. 5A is a block diagram of CDMA2000 packet data foreign mode withSimple IP; and

FIG. 5B is a call flow diagram that shows Simple IP operation in theCDMA2000 packet data foreign mode.

DETAILED DESCRIPTION

The word “exemplary” can be used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” can be not necessarily to be construed as preferred oradvantageous over other embodiments.

FIG. 1 is a block diagram of a system that comprises a home system 10,such as a CDMA 2000 packet data system or a GPRS system, a visitedsystem 20, such as a GPRS system or a CDMA 2000 packet data system, andan interface entity 30 or “IIF” that couples the home system 10 to thevisited system 20, and enables communication between the home system 10and the visited system 20.

The following sections describe architectures that can be adapted forCDMA2000/GPRS roaming scenarios, such as, GPRS foreign mode with MobileIPv4, GPRS foreign mode with Simple IPv4 or IPv6, CDMA2000 packet dataforeign mode with Mobile IPv4, and CDMA2000 packet data foreign modewith Simple IPv4 or IPv6.

GPRS Foreign Mode with Mobile IPv4

FIG. 2A is an exemplary block diagram of a GPRS foreign mode with MobileIPv4, and depicts the functions and control interface provided by an IIFin this embodiment. This roaming scenario occurs when a CDMA2000 packetdata native subscriber operates Mobile IPv4 [IS-835-C] in GPRS foreignmode. In this embodiment, the home system 10 can be a CDMA 2000 packetdata system wherein a CDMA 2000 packet data native subscriber roams to aGPRS system and uses Mobile IPv4. The home system 10 comprises a ANSI-41home location register 131, an AAA entity 116, and a home agent 135. Thevisited system 20 can be a GPRS system that comprises a SGSN 137.

The interface 30 or “IIF” comprises an ANSI-41 visited location register111 coupled to the ANSI-41 home location register 131 via a D interface113, a GSM home location register 124 coupled to the SGSN 137 via a Grinterface 123, a GGSN 126 coupled to the SGSN 137 via a Gp interface 127and coupled to the Internet via a Gi interface, an AAA entity 140coupled to the AAA entity 116 via an X3 interface 117, and a foreignagent 118 coupled to the home agent 135 via an X1 interface 115. The IIFprovides both GSM HLR and ANSI-41 VLR emulation to allow the subscriberto register. This interworking can be provided over the interfacereferences “Gr” and “D”. The IIF provides GGSN and FA emulation tosupport bearer connectivity between the visited and home networks viathe IIF. This interworking can be provided over the interface references“Gn” and “X1”. The IIF provides AAA emulation to interact with the homenetwork's AAA for Mobile IP Foreign Agent challenge authentication and3GPP2 packet data accounting. This interworking can be provided over theinterface reference “X3”.

If bearer connectivity between from the GPRS system and the CDMA2000packet data system is not required, then reverse tunneling on the X1interface is not required. Rather, MS-terminated traffic traversesthrough the X1 and Gp interfaces. In the case where reverse tunneling isnot required, the IIF routes MS-originated traffic, received on a Gpinterface, to the Internet directly via a Gi interface.

Thus, for a user homed in a CDMA Mobile IP system roaming to a GSMsystem, the IIF may present a GGSN interface to GSM and a FA and AAAinterfaces to the CDMA system. The IIF may serve as the endpoint for theGTP and Mobile IP tunnels, with a packet routing function between theGGSN and FA. The IIF may also provide an accounting function so thatoperators can charge based on configurable measurements such as packetcount, bandwidth, time of day, etc.

FIG. 2B is an exemplary call flow diagram that shows Mobile IPv4operation in the GPRS foreign mode. FIG. 2B depicts a call flow examplefor the roaming scenario where a CDMA2000 packet data native subscriberoperates Mobile IPv4 [IS-835-C] in the GPRS foreign mode. In thisexample, the MS has shared secrets with the home CDMA2000 system forMobile IP authentication. The MS may request the home CDMA2000 system toassign a HA and/or an IP address. The reverse tunneling can be enabledso that all data traffic (MS-originated and terminated) traversesthrough the IIF and home CDMA2000 system. The IIF generates 3GPP2 packetdata accounting records and sends it to the home CDMA2000 system viaRADIUS.

The MS performs GPRS attach with a SGSN. The authentication associatedwith the GPRS attach can be a SIM-based authentication requiring the Kisecret key. The IIF acts as the GSM HLR configured with the Ki secret.In any case, the IIF can be not required to communicate with the HLR inthe home CDMA2000 system for the authentication. (Step 1) The MS sendsthe Activate PDP Context Request to the SGSN. The message includes theAccess Point Name (APN). The APN has the format <NetworkID>.<MNC>.<MCC>.gprs. The Network ID (e.g., CDMA2000carrier.com)indicates to which external network the MS wants to establish a logicalconnection. The Requested PDP Address can be omitted in the message. TheMS has a static Mobile IP home address or obtains a new Mobile IP homeaddress. (Step 2) The SGSN selects a GGSN based on the APN. The SGSNuses the APN as the lookup name to query a DNS server (not shown in thefigure) and obtains a list of available GGSNs that can be used tosupport the requested APN. The APN's Network ID indicates a CDMA2000operator; thus, the DNS server returns with the IIF's IP address. (Step3) The SGSN sends the Activate PDP Context Request to the selected IIFto set up a PDP context for the MS. The message includes the APN, butthe Requested PDP Address can be omitted. (Step 4) The IIF acts as theGGSN and sends the Create PDP Context Response to the SGSN that in turnsends the Activate PDP Context Accept to the MS. The PDP Address in bothmessages can be set to 0.0.0.0 to indicate that the PDP address will beassigned later after successful Mobile IP registration. (Step 5) The IIFacts as the FA and sends one or more Mobile IP Agent Advertisements tothe MS, because the omission of the Requested PDP Address in theActivate PDP Context Request can be the indication that the MS wishes touse Mobile IP. The Agent Advertisement can be sent over the establishedPDP context. The Agent Advertisement contains the FA Care-of Address andthe FA Challenge (FAC). (Step 6)

The MS sends the Mobile IP Registration Request to the IIF over the PDPcontext. The following information can be contained in the RegistrationRequest: MS's NAI [RFC 2794] has the format of <username>@<domain name>,where the domain name identifies the MS's home CDMA2000 system. MS-HAauthenticator can be computed based on the content of the RegistrationRequest and the secret shared between the MS and HA [RFC 2002]. MS-AAAauthenticator can be computed based on the FAC and the secret sharedbetween the MS and home AAA server [RFC 3012]. The HA Address field canbe set to a known value if the MS uses a permanent HA, or to 0.0.0.0 ifthe MS wants a new HA assigned by the home network. Home Address fieldcan be set to a known value if the MS uses a permanent address, or to0.0.0.0 if the MS wants a new address assigned by the HA. The T-bit canbe set to one to enable a reverse tunnel from the IIF to the MS's HA.(Step 7) The IIF acts as the RADIUS client and sends a RADIUSAccess-Request to the home AAA server. The RADIUS Access-Request conveysMS's NAI, FAC authenticator, FAC, HA address, etc. [IS-835]. (Step 8) Ifthe authentication is successful, the home AAA server responds with theRADIUS Access-Accept that includes the MS's HA address. (Step 9) The IIFacts as the FA and forwards the Mobile IP Registration Request to the HAaddress contained in the RADIUS Access-Accept. (Step 10) The HA verifiesthe MS-HA authenticator in the Mobile IP Registration Request. If the HAdoesn't have the shared secret, as in the case of dynamically assignedHA, it communicates with the home AAA server for the shared secret. TheHA responds to the Mobile IP Registration Request with the Mobile IPRegistration Reply containing a registration result (e.g., successful oran error code). If the MS wishes for a new home address, a new addresscan be returned in the Registration Reply; otherwise, the MS's permanentaddress can be returned. (Step 11) The IIF acts as the FA and forwardsthe Mobile IP Registration Reply to the MS over the appropriate PDPcontext. The IIF FA functionality notes the assigned MS IP address andshares that address with the IIF GGSN functionality. (Step 12)

The IIF acts as the GGSN and updates its PDP context by setting the PDPaddress to the MS's home address (as indicated in the Registration Replyand shared by the FA functionality). The PDP address (hence the MS'shome address) can be associated with a GTP tunnel identified by theTunnel Endpoint ID (TEID). (Step 13) The IIF acts as the GGSN andtriggers the GGSN-initiated PDP Context modification procedure in orderto update the PDP address in the SGSN and MS [3GPP TS 29.061]. The IIFsends the Update PDP Context Request to the SGSN that forwards it to theMS. (Step 14) The MS responds with the Update PDP Context Response tothe SGSN that forwards it to the IIF. (Step 15) The IIF acts as theRADIUS client and sends the RADIUS Accounting-Request (Start) to thehome AAA server [IS-835]. 3GPP2-vendor-specific attributes are used toconvey accounting records, but some airlink record attributes (e.g.,service option, mux option, etc.) are not applicable. (Step 16) The homeAAA server responds with a RADIUS Accounting-Response (Start). (Step 17)Bearer traffic traverses through the IIF in both directions, if reversetunneling from the IIF to HA is enabled. For routing MS-originatedpackets, the IIF routes packets received from the MS's GTP tunnel(identified by a TEID) to the MS's HA via a Mobile IP reverse tunnel.For routing MS-terminated packets, the IIF routes packets received fromthe HA-to-FA tunnel to the MS's GTP tunnel. IPsec can be used to protectthe Mobile IP tunnels between HA and IIF, and the GTP tunnels betweenIIF and SGSN. (Step 18)

GPRS Foreign Mode with Simple IP

FIG. 3A is an exemplary block diagram of a GPRS foreign mode with SimpleIP that shows a roaming scenario where a CDMA2000 packet data nativesubscriber operates IPv4 or IPv6 in the GPRS foreign mode. FIG. 3A alsodepicts the functions and control interface provided by an interface orIIF in this case. In this embodiment, the home system 10 can be a CDMA2000 packet data system wherein a CDMA 2000 packet data nativesubscriber roams to a GPRS system and uses Simple IP. The home system 10comprises a ANSI-41 home location register 131, an AAA entity 116, and aLNS 139. The visited system 20 can be a GPRS system that comprises aSGSN 137.

The interface 30 or “IIF” comprises an ANSI-41 visited location register111 coupled to the ANSI-41 home location register 131 via a D interface113, a GSM home location register 124 coupled to the SGSN 137 via a Grinterface 123, a GGSN 126 coupled to the SGSN 137 via a Gp interface 127and coupled to the Internet via a Gi interface, an AAA entity 140coupled to the AAA entity 116 via an X3 interface 117, and a LAC entity109 coupled to the LNS 139 via an X2 interface 119. The IIF providesboth GSM HLR and ANSI-41 VLR emulation to allow the subscriber toregister. This interworking can be provided over the interfacereferences “Gr” and “D.” The IIF provides GGSN and LAC emulation tosupport bearer connectivity between the visited and home networks viathe IIF. This interworking can be provided over the interface references“Gn” and “X2.” The IIF provides AAA emulation to interact with the homenetwork's AAA for L2TP authentication and 3GPP2 packet data accounting.This interworking can be provided over the interface reference “X3.”

If bearer connectivity between the CDMA2000 packet data system and GPRSsystem is not required, then the X2 interface is not required. The IIFstill supports a Gp interface to the SGSN and provides Internet accessvia a Gi interface (not shown in the figure).

Thus, for a user homed in a CDMA Simple IP system roaming to a GSMsystem, the IIF may present a GGSN interface to GSM and a normal routinginterface to the CDMA system. The IIF may serve as the endpoint for theGTP and IPSec tunnels, with a packet routing function between the GGSNand the CDMA system. The IIF may also provide an accounting function sothat operators can charge based on configurable measurements such aspacket count, bandwidth, time of day, etc.

FIG. 3B is an exemplary call flow diagram that shows Simple IP operationin the GPRS foreign mode, and explains a roaming scenario where aCDMA2000 packet data native subscriber operates Simple IP in the GPRSforeign mode. In this example, the MS has shared secrets with the homeCDMA2000 system for Simple IP authentication (i.e., CHAP). The MSestablishes a PPP session, via L2TP, to the home CDMA2000 system. Duringthe PPP establishment, the home CDMA2000 system assigns an IP address tothe MS dynamically. All the MS's data traffic (MS-originated and—MSterminated) traverses through the IIF and home CDMA2000 system. The IIFgenerates 3GPP2 packet data accounting records and sends it to the homeCDMA2000 system via RADIUS.

The MS performs GPRS attach with a SGSN. The authentication associatedwith the GPRS attach can be a SIM-based authentication requiring the Kisecret. The IIF acts as the GSM HLR configured with the Ki secret or theGSM VLR. In any case, the IIF can be not required to communicate withthe HLR in the home CDMA2000 system for the authentication. (Step 1) TheMS sends the Activate PDP Context Request to the SGSN. The messageincludes the APN (Access Point Name). The APN has the format <NetworkID>.<MNC>.<MCC>.gprs. The Network ID (e.g., CDMA2000carrier.com)indicates to which external network the MS wants to establish a logicalconnection. The Requested PDP Address can be omitted in the message sothat the IIF (acting as a GGSN) later will not assign an IP address tothe MS; instead, the address will be assigned by the LNS. (Step 2) TheSGSN selects a GGSN based on the APN. The SGSN queries a DNS server (notshown in the figure) and obtains a list of available GGSNs that can beused to support the requested APN. In this case, the APN's Network IDindicates a CDMA2000 operator; thus, the DNS server returns with theIIF's IP address. (Step 3)

The SGSN sends the Activate PDP Context Request to the selected IIF toset up a PDP context for the MS. The message includes the APN, but theRequested PDP Address can be omitted. (Step 4) The IIF acts as the GGSNand sends the Create PDP Context Response to the SGSN that in turn sendsthe Activate PDP Context Accept to the MS. The PDP Address in bothmessages can be set to 0.0.0.0 to indicate that the PDP address will bereset later. (Step 5)

After the PDP context can be established, the MS and IIF perform PPP LCPnegotiation. The IIF LAC functionality establishes L2TP tunnels with aLNS. The IIF determines which LNS based on the requested APN. The IIF isconfigured with the LNS information (e.g., LNS's IP address)corresponding to an APN. After the L2TP tunnel establishment, the IIFLAC functionality forwards LCP information between the LNS and MS.During the LCP negotiation, the LNS and MS negotiate PAP or CHAP as theprotocol for PPP authentication. (Step 6) PPP authentication (PAP orCHAP) is performed. The MS's credential is authenticated by the home AAAin the CDMA2000 system. The RADIUS interaction between the LNS and homeAAA is not shown in the figure. (Step 7) The LNS and MS perform PPP IPCPnegotiation. The IIF LAC functionality relays IPCP messages between theL2TP tunnel and PDP context. During the negotiation, the LNS assigns anIP address to the MS. The IIF monitors for this address and uses it asthe MS's PDP address. (Step 8)

The IIF also needs to notify the SGSN and MS about the updated PDPaddress. Recall that the PDP address can be set to 0.0.0.0 initially.Therefore, the IIF sends the Update PDP Context Request to the SGSN thatforwards it to the MS. (Step 9) The MS responds with the Update PDPContext Response to the SGSN that forwards it to the IIF. (Step 10)

The IIF acts as the RADIUS client and sends the RADIUSAccounting-Request (Start) to the home AAA server [IS-835].3GPP2-vendor-specific attributes are used to convey accounting records,but some airlink record attributes (e.g., service option, mux option,etc.) are not applicable. (Step 11) The home AAA server responds withthe RADIUS Accounting-Response (Start). (Step 12) Bearer traffictraverses through the IIF in both directions. For routing MS-originatedpackets, the IIF routes packets received from the MS's GTP tunnel(identified by a TEID) to the MS's L2TP tunnel/session. For routingMS-terminated packets, the IIF routes packets received from the MS'sL2TP tunnel/session to the MS's GTP tunnel. IPsec can be used to protectthe L2TP tunnel/session between LNS and IIF, and the GTP tunnels betweenIIF and SGSN. (Step 13)

CDMA2000 Packet Data Foreign Mode with Mobile IPv4

FIG. 4A is an exemplary block diagram of a CDMA2000 packet data foreignmode with Mobile IPv4. This section describes the roaming scenario wherea GPRS native subscriber operates Mobile IPv4 [IS-835-C] in the CDMA2000packet data foreign mode. FIG. 4A also depicts the functions and controlinterface provided by the IIF in this case. In this embodiment, the homesystem 10 can be a GPRS system. A GPRS native subscriber roams to a CDMA2000 packet data system and uses Simple IP. The home system 10 comprisesa GSM home location register 124, a GGSN 126, and an AAA entity 128. Thevisited system 20 can be a CDMA 2000 packet data system that comprises aANSI-41 visited location register 111, an AAA entity 116, and a packetdata serving node/foreign agent 118.

The interface 30 or “IIF” comprises an ANSI-41 home location register131 coupled to the ANSI-41 visited location register 111 via a Dinterface 113, a GSM visited location register 133 coupled to the GSMhome location register 124 via a D interface 121, a SGSN 137 coupled tothe GGSN 126 via a Gp interface 127, an AAA entity 140 coupled to theAAA entity 128 via a X4 interface 129 and coupled to the AAA entity 116via a X3 interface 117, and a home agent 135 coupled to the packet dataserving node/foreign agent 118 via a X1 interface 115. The IIF providesboth GSM VLR and ANSI-41 HLR emulation to allow the subscriber toregister. This interworking can be provided over the interface reference“D”. The IIF provides HA and SGSN emulation to support bearerconnectivity between the visited and home networks via the IIF. Thisinterworking can be provided over the interface reference “X1” and “Gn”.The IIF provides AAA emulation to interact with the visited network'sAAA for Mobile IP authentication and 3GPP2 packet data accounting. TheIIF also may interact with the home network's AAA for 3GPP packet dataaccounting. This interworking can be provided over the interfacereference “X3” and “X4”. The IIF/AAA requirements for CDMA2000 packetdata foreign mode with mobile IP will be described below in greaterdetail.

If bearer connectivity between the visited CDMA2000 packet data systemand home GPRS system is not required, the Gp interface is not required.In this case, mobile-originated data traffic can be routed directly tothe Internet via the PDSN/FA in the visited system, or via the IIF/HA ifreverse tunneling is enabled. Mobile-terminated data traffic is routedto the PDSN/FA via the IIF/HA. The interface X3 and X4 are required forthe IIF to interwork AAA messages between the CDMA2000 AAA server andGPRS AAA server.

Thus, for a user homed in a GSM system roaming to a CDMA Mobile IPsystem, the IIF may present a HA interface to the CDMA system and a SGSNinterface to the GSM system. A subset of SGSN functions is requiredincluding APN resolution. The IIF may serve as the endpoint for theMobile IP and GTP tunnels, with a packet routing function between the HAand SGSN functions.

FIG. 4B is an exemplary call flow diagram that shows Mobile IPv4operation in the CDMA2000 packet data foreign mode. This call flowexample shows a roaming scenario where a GPRS native subscriber operatesMobile IPv4 [IS-835-C] in the CDMA2000 packet data foreign mode. In thisexample, the home GPRS system doesn't support HA; thus, the MS hasshared secrets with the IIF for Mobile IP authentication. The home GPRSsystem dynamically assigns an IP address to the MS. All MS's datatraffic (MS-originated and MS-terminated) traverses through the IIF andhome GPRS system. The IIF receives 3GPP2 accounting records from thevisited CDMA2000 system and may map them to 3GPP accounting records andforward them to the home GPRS system via RADIUS.

The MS originates SO 33 and establishes a PPP session with the PDSN/FA.(Step 1) The PDSN/FA sends one or more Mobile IP Agent Advertisements tothe MS, because the omission of the IP-Address Configuration Optionduring the PPP IPCP negotiation indicates that the MS wishes to useMobile IP. The Agent Advertisement contains the FA Care-of Address andthe FA Challenge (FAC). (Step 2)

The MS sends the Mobile IP Registration Request to the PDSN/FA. Thefollowing information can be contained in the Registration Request: MS'sNAI [RFC 2794] has the format of <username>@<domain name>, where thedomain name identifies the MS's home GPRS system. MS-HA authenticatorcan be computed based on the content of the Registration Request and thesecret shared between the MS and HA [RFC 2002]. MS-AAA authenticator canbe computed based on the FAC and the secret shared between the MS andhome AAA server [RFC 3012]. The HA Address field can be set to a knownvalue if the MS uses a permanent HA, or to 0.0.0.0 if the MS wants a newHA assigned by the home network. The HA field can be set to 0.0.0.0 torequest a new address assigned by the HA. The T-bit can be set to one torequest the PDSN/FA to establish a reverse tunnel to the MS's HA. (Step3)

The PDSN/FA generates a RADIUS Access-Request conveying MS's NAI, FACauthenticator, FAC, HA address, etc. [IS-835]. Because the domain nameof the MS's NAI indicates a GPRS system, the PDSN/FA sends a RADIUSAccess-Request to the IIF via the AAA in the CDMA2000 system. The IIFmay modify the message in accordance with [3GPP TS 29.061]. (Step 4) Ifthe authentication is successful, the home AAA server responds with theRADIUS Access-Accept. The message is routed back to the PDSN via IIF andvisited AAA. The IIF may modify the message in accordance with[P.S0001-A V3.0]. (Step 5) The PDSN/FA forwards the Mobile IPRegistration Request to the HA function in the IIF. The IIF verifies theMS-HA authenticator in the Mobile IP Registration Request. (Step 6)

If the authentication is successful, the IIF SGSN functionalityestablishes GTP tunnels with a GGSN in the home GPRS system and canrequest an IP address from the GGSN. The IIF SGSN functionality derivesan APN that has the format <Network ID>.mnc<MNC>.mcc<MCC>.gprs [TS23.003]. The <Network ID> is the realm portion of the MS's NAI andindicates which GGSN the MS wants to access for the requested service.The <MNC> and <MCC> are derived from the MS's IMSI. The MS's NAI andIMSI are available from the RADIUS Access-Request in step 4. The SGSNfunctionality uses the derived APN as the lookup name to query GPRS DNSserver (not shown in the figure) and from it obtains a list of availableGGSNs that can be used to support the requested service. The IIF SGSNfunctionality sends the Create PDP Context Request to the selected GGSN.The Requested PDP Address in the message is set to 0.0.0.0 to request anew IP address. (Step 7) The GGSN responds with the Create PDP ContextResponse including the new IP address assigned to the MS. (Step 8) TheIIF acts as the HA and sends the Mobile IP Registration Reply to the MSvia the PDSN/FA. The Home Address field in the Mobile IP RegistrationReply can be set to the IP address assigned by the GGSN. (Step 9) ThePDSN sends the RADIUS Accounting-Request (Start) containing 3GPP2 packetdata accounting information [P.S0001-A V3.0]. Because the domain name ofthe MS's NAI indicates a GPRS system, the RADIUS Accounting-Request(Start) is routed to the home AAA in the GPRS system via the visited AAAand IIF. The IIF may modify the message in accordance with [3GPP TS29.061]. (Step 10) The IIF acts as the RADIUS server and replies withthe RADIUS Accounting-Response (Start). (Step 11)

Bearer traffic traverses through the IIF in both directions. For routingMS-originated packets, the IIF routes packets received from the MobileIP reverse tunnel to the MS's GTP tunnel (identified by a TEID). Forrouting MS-terminated packets, the IIF routes packets received from theGTP tunnel to a HA-to-FA tunnel. IPsec can be used to protect the MobileIP tunnels between PDSN/FA and IIF, and the GTP tunnels between IIF andGGSN. (Step 12)

IIF/AAA REQUIREMENTS for CDMA2000 Packet Data Foreign Mode with MobileIP

The IIF requirements to process the RADIUS Access-Request received fromthe visited CDMA2000 packet data system will now be described.

The IIF proxies all IETF RADIUS attributes without modification, exceptthe Calling-Station-ID attribute, Called-Station-ID attribute, andFramed-Protocol attribute. The processing of these three attributes isdescribed below. If the Calling-Station-ID attribute in the receivedRADIUS Access-Request contains IMSI, the IIF copies the IMSI into the3GPP-IMSI attribute [3GPP TS 29.061] and include it in the RADIUSAccess-Request destined for the MS's home GPRS system. The IIF does notinclude the Calling-Station-ID attribute in the RADIUS Access-Requestsent to the home AAA in the GPRS system. If the Calling-Station-IDattribute in the received RADIUS Access-Request contains MIN or IRM, theIIF maps it to the MS's IMSI used in the home GPRS system and include itin the 3GPP-IMSI attribute of the RADIUS Access-Request destined for thehome GPRS system. The IIF does not include the Calling-Station-IDattribute in the RADIUS Access-Request sent to the home AAA in the GPRSsystem.

The IIF includes the Called-Station-ID attribute in the RADIUSAccess-Request destined for the MS's home GPRS system. The Value fieldof the Called-Station-ID attribute is set to the APN (see section8.3.4). If the Framed-Protocol attribute is included in the receivedRADIUS Access-Request, the IIF overrides the value to 7 [3GPP TS29.061]. The IIF removes all 3GPP2 VSAs from the received RADIUSAccess-Request. The IIF is not required to include any 3GPP VSAs, exceptthe 3GPP-IMSI attribute, in the transmitted RADIUS Access-Requestdestined for the MS's home GPRS system.

The IIF requirements to process the RADIUS Access-Accept received fromthe MS's home GPRS system will now be described.

The IIF proxies all IETF RADIUS attributes without modification. The IIFremoves all 3GPP VSAs from the received RADIUS Access-Accept, beforetransmitting the RADIUS Access-Accept to the visited CDMA2000 packetdata system.

If the policy of the home GPRS system requires the roaming MS's datatraffic to traverse through the home GPRS system via the IIF, and theHA-Address VSA was included in the corresponding RADIUS Access-Requestreceived earlier from the visited CDMA2000 packet data system, the IIFincludes the Reverse-Tunnel-Specification VSA in the transmitted RADIUSAccess-Accept destined for the visited CDMA2000 packet data system. Thevalue field of the VSA is set to 1 indicating that reverse tunneling isrequired.

The IIF requirements to process the RADIUS Accounting-Request START andAccounting-Request INTERIM are the same as the requirements to processthe RADIUS Access-Request.

The IIF requirements to process the RADIUS Accounting-Request STOP arethe same as the requirements to process the RADIUS Access-Request withthe following additional requirements: If the Session-Continue VSA isset to FALSE in the received RADIUS Accounting-Request STOP, and if theIIF has not previously received an Accounting-Request (Start) fromanother PDSN with the same IP Address (for the case of inter-PDSNhandoff with Mobile IP), the IIF inserts the 3GPP-Session-Stop-IndicatorVSA to indicate that the PDP session has been terminated.

CDMA2000 Packet Data Foreign Mode with Simple IP

FIG. 5A is an exemplary block diagram of a CDMA2000 packet data foreignmode with Simple IP. This section describes the roaming scenario where aGPRS native subscriber operates IPv4 or IPv6 in the CDMA2000 packet dataforeign mode. FIG. 5A also depicts the functions and control interfaceprovided by the interface 30 or “IIF” in this case. In this embodiment,the home system 10 can be a GPRS system wherein a GPRS native subscriberroams to a CDMA 2000 packet data system and uses Mobile IPv4. The homesystem 10 comprises a GSM home location register 124, a GGSN 126, and anAAA entity 128. The visited system 20 can be a CDMA 2000 packet datasystem that comprises a ANSI-41 visited location register 111, an AAAentity 116, and a home system 109.

The interface 30 or “IIF” comprises an ANSI-41 home location register131 coupled to the ANSI-41 visited location register 111 via a Dinterface 113, a GSM visited location register 133 coupled to the GSMhome location register 124 via a D interface 121, a SGSN 137 coupled tothe GGSN 126 via a Gp interface 127, an AAA entity 140 coupled to theAAA entity 128 via a X4 interface 129 and coupled to the AAA entity 116via a X3 interface 117, and a LCS entity 139 coupled to the packet dataserving node/LAC entity 109 via an X2 interface 119. The IIF providesboth GSM VLR and ANSI-41 HLR emulation to allow the subscriber toregister. This interworking can be provided over the interface reference“D”. The IIF provides LNS and SGSN emulation to support bearerconnectivity between the visited and home networks via the IIF. Thisinterworking can be provided over the interface reference “X2” and “Gn”.The IIF provides AAA emulation to interact with the visited network'sAAA for L2TP authentication and 3GPP2 packet data accounting. The IIFalso may interact with the home network's AAA for 3GPP packet dataaccounting. This interworking can be provided over the interfacereference “X3” and “X4”. The IIF/AAA requirements for CDMA2000 packetdata foreign mode with Simple IP will be described below in greaterdetail.

If bearer connectivity between the visited CDMA2000 packet data systemand home GPRS system is not required, the X2 and Gp interface are notrequired. In this case, both mobile-originated and mobile-terminateddata traffic is routed to/from the Internet via the PDSN in the visitedsystem. The interface X3 and X4 are required for the IIF to interworkAAA messages between the CDMA2000 AAA server and GPRS AAA server.

Thus, for a user homed in a GSM system roaming to a CDMA Simple IPsystem, the IIF may present a L2TP Network Server (LNS) interface to theCDMA system and a SGSN interface to the GSM system. A subset of SGSNfunctions is required including APN resolution. The IIF may serve as theendpoint for the Mobile L2TP and GTP tunnels, with a packet routingfunction between the LNS and SGSN functions.

FIG. 5B is an exemplary call flow diagram that shows Simple IP operationin the CDMA2000 packet data foreign mode. This call flow exampleillustrates a roaming scenario where a GPRS native subscriber operatesSimple IP in the CDMA2000 packet data foreign mode. In this example, theMS has shared secrets with the home AAA in the GPRS system for CHAPauthentication. The home GPRS system dynamically assigns an IP addressto the MS. All MS's data traffic (MS-originated and mobile terminated)traverses through the IIF and home GPRS system. The IIF receives 3GPP2accounting records from the visited CDMA2000 system and maps it to 3GPPaccounting records and forward it to the home GPRS system via RADIUS.

The MS originates SO 33 and initiates PPP LCP negotiation with thePDSN/LAC. CHAP can be negotiated as the protocol for PPP authentication.(Step 1) PDSN/LAC sends a CHAP challenge to the MS. (Step 2) The MSreplies with its NAI and a challenge response computed based on thechallenge and the secret shared with the home AAA in the GPRS system.The PDSN/LAC sends RADIUS Access-Request. Because the domain name of theMS's NAI indicates a GPRS system, the RADIUS Access-Request can berouted through the visited AAA and IIF that proxies the message to thehome AAA in the GPRS system. The IIF may modify the message inaccordance with [3GPP TS 29.061]. (Step 3) If the authentication issuccessful, the home AAA responds with the RADIUS Access-Accept. Themessage can be routed back to the PDSN/LAC via the IIF and visited AAA.The IIF inserts the Tunnel-Server-Endpoint attribute in the RADIUSAccess-Accept. This attribute informs the PDSN/LAC to establish a L2TPtunnel with the IIF that acts as the LNS. The PDSN/LAC sends the CHAPSuccess to inform the MS about the successful authentication. (Step 4)

The PDSN/LAC establishes a L2TP tunnel/session with the IIF that acts asthe LNS. During the L2TP tunnel/session establishment, the PDSN/LACforwards the LCP information (exchanged between the MS and PDSN/LAC) tothe IIF. The IIF LNS functionality may initiate CHAP challenge (notshown in the figure) to authenticate the MS before IPCP negotiation.(Step 5) The IIF SGSN functionality establishes GTP tunnels with a GGSNin the home GPRS system and can request an IP address from the GGSN. TheIIF derives an APN that has the format <NetworkID>.mnc<MNC>.mcc<MCC>.gprs. The <Network ID> is the realm portion of theMS's NAI and is used to indicate which GGSN the MS wants to access forthe requested service. The <MNC> and <MCC> are derived from the MS'sIMSI. The MS's NAI and IMSI are available from the RADIUS Access-Requestin step 3. The IIF SGSN functionality uses the derived APN as the lookupname to query GPRS DNS server (not shown in the figure) and obtains alist of available GGSNs that can be used to support the requestedservice. The IIF SGSN functionality sends the Create PDP Context Requestto the selected GGSN. The Requested PDP Address in the message is set to0.0.0.0 to request a new IP address. (Step 6) The GGSN responds with theCreate PDP Context Response including the new IP address assigned to theMS. (Step 7)

This new IP address can be assigned to the MS during the PPP IPCPnegotiation between the IIF and MS. (Step 8) The PDSN/FA sends theRADIUS Accounting-Request (Start) containing 3GPP2 packet dataaccounting information [IS-835]. The PDSN sends the RADIUSAccounting-Request (Start) containing 3GPP2 packet data accountinginformation [P.S0001-A V3.0]. Because the domain name of the MS's NAIindicates a GPRS system, the RADIUS Accounting-Request (Start) is routedto the home AAA in the GPRS system via the visited AAA and IIF. The IIFmay modify the message in accordance with [3GPP TS 29.061]. (Step 9) Thehome AAA replies with the RADIUS Accounting-Response (Start) that isrouted back to the PDSN via IIF and visited AAA. (Step 10)

Bearer traffic traverses through the IIF in both directions. For routingMS-originated packets, the IIF routes packets received from the MS'sL2TP tunnel/session to the MS's GTP tunnel (identified by a TEID). Forrouting MS-terminated packets, the IIF routes packets received from theMS's GTP tunnel to the MS's L2TP tunnel/session. IPsec can be used toprotect the L2TP tunnel/session between PDSN/LAC and IIF, and the GTPtunnels between IIF and GGSN. (Step 11)

IIF/AAA Requirements for CDMA2000 Packet Data Foreign Mode with SimpleIP

The IIF requirements to process the RADIUS Access-Request are the sameas the requirements to process the RADIUS Access-Request for theCDMA2000 Packet Data Foreign Mode with Mobile IP, described above.

The IIF requirements to process the RADIUS Access-Accept are similar tothe requirements for processing the RADIUS Access-Accept for theCDMA2000 Packet Data Foreign Mode with Mobile IP, however, if the policyof the home GPRS system requires the roaming MS's data traffic totraverse through the home GPRS system via the IIF, and the HA-AddressVSA was not included in the corresponding RADIUS Access-Request receivedearlier from the visited CDMA2000 packet data system, the IIF insertsthe Tunnel-Server-Endpoint, Tunnel-Type, and Tunnel-Medium-Typeattributes in the transmitted RADIUS Access-Accept destined for thevisited CDMA2000 packet data system. The Tunnel-Server-Endpointattribute indicates the IIF/LNS address. The Tunnel-Type attributeindicates L2TP. The Tunnel-Medium-Type attribute indicate IPv4.

The IIF requirements to process the RADIUS Accounting-Request START andAccounting-Request INTERIM are the same as the requirements to processthe RADIUS Accounting-Request START and Accounting-Request INTERIM forthe CDMA2000 Packet Data Foreign Mode with Mobile IP, described above.

The IIF requirements to process the RADIUS Accounting-Request STOP arethe substantially the same as the requirements to process the RADIUSAccounting-Request STOP for the CDMA2000 Packet Data Foreign Mode withMobile IP, however, if the Session-Continue VSA is set to FALSE in thereceived RADIUS Accounting-Request STOP, and the IP-Technology VSAindicates Simple IP, the IIF inserts the 3GPP-Session-Stop-Indicator VSAto indicate that the PDP session has been terminated.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the embodiments disclosed herein may be implemented aselectronic hardware, computer software, or combinations of both. Toclearly illustrate this interchangeability of hardware and software,various illustrative components, blocks, modules, circuits, and stepshave been described above generally in terms of their functionality.Whether such functionality can be implemented as hardware or softwaredepends upon the particular application and design constraints imposedon the overall system. Skilled artisans may implement the describedfunctionality in varying ways for each particular application, but suchimplementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with a general purpose processor, a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with theembodiments disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium can be coupled to the processor such theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal.

The previous description of the disclosed embodiments can be provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention can be notintended to be limited to the embodiments shown herein but can be to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

1. An apparatus for enabling communications between a CDMA (CodeDivision Multiple Access) packet data system and a GPRS (General PacketRadio Service) system, wherein a CDMA 2000 packet data native subscriberusing Mobile IPv4 (Internet Protocol version 4) roams from a home CDMA2000 packet data system to a visited GPRS system comprising a SGSN(Serving GPRS Support Node), comprising: means for coupling the homesystem to the visited system to enable communication between the homesystem and the visited system, wherein the home CDMA 2000 packet datasystem comprises a ANSI (American National Standards Institute)-41 homelocation register, an AAA (Authentication, Authorization, andAccounting) entity, and a home agent; and means for providing a distinctinterface for each of the ANSI-41 home location register, the AAAentity, and the home agent.
 2. The apparatus according to claim 1,wherein the home CDMA 2000 packet data system comprises a ANSI-41 homelocation register, an AAA entity, and a home agent, further comprising:means for allowing a subscriber to register over a first interface; andallowing the subscriber to register over a second interface.
 3. Theapparatus according to claim 1, further comprising: means for supportingbearer connectivity between the visited system and the home system suchthat a foreign agent interface and an AAA interface are presented to theCDMA 2000 packet data system over a third interface; and means forsupporting bearer connectivity between the visited system and the homesystem such that a GGSN (Gateway GPRS Support Node) interface ispresented to the visited system over a fourth interface.
 4. Theapparatus according to claim 3, further comprising: means for providingan endpoint for a GTP (GPRS Tunneling Protocol) tunnel and a Mobile IPtunnel.
 5. The apparatus according to claim 4, further comprising: meansfor providing a packet routing function between the GGSN interface and aforeign agent interface.
 6. The apparatus according to claim 1, furthercomprising: means for providing an accounting function by interactingwith a home network's AAA for Mobile IP Foreign Agent challengeauthentication and 3GPP2 (3rd Generation Partnership Project 2) packetdata accounting.
 7. The apparatus for enabling communications between aCDMA (Code Division Multiple Access) packet data system and a GPRS(General Packet Radio Service) system, wherein a CDMA 2000 packet datanative subscriber using Simple IP roams from a home CDMA 2000 packetdata system to a visited GPRS system comprising a SGSN, (Serving GPRSSupport Node) comprising: means for coupling the home system to thevisited system to enable communication between the home system and thevisited system, wherein the home CDMA 2000 packet data system comprisesa ANSI-41 home location register, an AAA (Authentication, Authorization,and Accounting) entity, and a LNS (Layer 2 Tunneling Protocol NetworkServer); and means for providing a distinct interface for each of theANSI-41 home location register, the AAA entity, and LNS.
 8. Theapparatus according to claim 7, further comprising: means for allowing asubscriber to register over a first interface; and allowing thesubscriber to register over a second interface.
 9. The apparatusaccording to claim 8, further comprising: means for supporting bearerconnectivity between the visited and home networks over a thirdinterface; and means for supporting bearer connectivity between thevisited and home networks over a fourth interface by presenting a GGSNinterface to the visited system and presenting a normal routinginterface to the CDMA 2000 packet data system to thereby provide apacket routing function between the GGSN interface and the home system.10. The apparatus according to claim 9, further comprising: means forproviding an endpoint for a GTP tunnel and an IPSec tunnel.
 11. Theapparatus according to claim 10, further comprising: means for providingan accounting function by interacting with the home network's AAA forL2TP (Layer 2 Tunneling Protocol) authentication and 3GPP2 packet dataaccounting over a fifth interface.
 12. An apparatus for enablingcommunications between a CDMA (Code Division Multiple Access) packetdata system and a GPRS (General Packet Radio Service) system, wherein aGPRS native subscriber using Mobile IPv4 (Internet Protocol version 4)roams from a home GPRS system to a visited CDMA 2000 packet data systemthat comprises an ANSI-41 visited location register, an AAA(Authentication, Authorization, and Accounting) entity, and a packetdata serving node/foreign agent, comprising: means for coupling the homesystem to the visited system to enable communication between the homesystem and the visited system, wherein the home GPRS system comprises aGSM home location register, a GGSN, and an AAA entity; and means forproviding a distinct interface for each of the GSM home locationregister, the GGSN, and the AAA entity.
 13. The apparatus according toclaim 12, further comprising: means for presenting a home agentinterface to the visited system; and means for presenting a SGSNinterface to the home system to support bearer connectivity between thevisited and home networks by providing a packet routing function betweenthe SGSN interface and the home agent interface.
 14. The apparatusaccording to claim 13, further comprising: means for providing endpointsfor a GTP tunnel and a Mobile IP tunnel.
 15. The apparatus according toclaim 13, further comprising: means for allowing a subscriber toregister.
 16. The apparatus according to claim 15, further comprising:means for interacting with the visited network's AAA for Mobile IPauthentication and 3GPP2 packet data accounting over a fifth interface;and means for interacting with the home network's AAA for 3 GPP packetdata accounting over a fourth interface.
 17. An apparatus for enablingcommunications between a CDMA (Code Division Multiple Access) packetdata system and a GPRS (General Packet Radio Service) system, wherein aGPRS native subscriber using Simple IP roams from home GPRS system to avisited CDMA 2000 packet data system that comprises a ANSI-41 visitedlocation register, a AAA (Authentication, Authorization, and Accounting)entity, and a PDSN/LAC (Packet Data Serving Node/Layer 2 TunnelingProtocol Access Concentrator) entity, comprising: means for coupling thehome system to the visited system to enable communication between thehome system and the visited system, wherein the home GPRS systemcomprises a GSM home location register, a GGSN, and an AAA entity; andmeans for providing a distinct interface for each of the GSM homelocation register, the GGSN, and the AAA entity.
 18. The apparatusaccording to claim 17, further comprising: means for supporting bearerconnectivity between the visited and home networks by providing a packetrouting function.
 19. The apparatus according to claim 18, furthercomprising: means for presenting a SGSN interface to the home system;means for presenting a L2TP Network Server (LNS) interface to thevisited system; and means for providing the packet routing functionbetween a SGSN emulation module and a LNS emulation module.
 20. Theapparatus according to claim 19, further comprising: means for providingendpoints for a GTP tunnel and a Mobile L2TP tunnel.
 21. The apapratusaccording to claim 20, further comprising: allowing a subscriber toregister.
 22. The apparatus according to claim 21, further comprising:means for interacting with the visited network's AAA entity, over anfifth interface, for L2TP authentication and 3GPP2 packet dataaccounting; and means for interacting with the home network's AAAentity, over an sixth interface, for 3GPP packet data accounting.
 23. Anapparatus for enabling communication between a home CDMA 2000 packetdata system and a visited GPRS (General Packet Radio Service) systemcomprising a SGSN (Serving GPRS Support Node), when a CDMA 2000 packetdata native subscriber using Mobile IPv4 roams to a visited GPRS system,the apparatus comprising: means for allowing a subscriber to registerover a first interface that couples a GSM home location registeremulation module to the SGSN; and means for allowing the subscriber toregister over a second interface that couples an ANSI-41 visitedlocation register emulation module to a ANSI-41 home location register.24. The apparatus according to claim 23, wherein the home CDMA 2000packet data interface entity comprises a ANSI-41 home location register,an AAA entity, and a home agent.
 25. The apparatus according to claim23, further comprising: means for coupling the home agent to a foreignagent emulation module via a third interface, wherein the foreign agentemulation module supports bearer connectivity between the visitedinterface entity and the home interface entity such that a foreign agentinterface and an AAA interface are presented to the CDMA 2000 packetdata interface entity over the third interface; and means for coupling aGGSN emulation module to the SGSN via a fourth interface, wherein theGGSN emulation module supports bearer connectivity between the visitedinterface entity and the home interface entity such that a GGSNinterface is presented to the visited interface entity over the fourthinterface.
 26. The apparatus according to claim 25, further comprising:means for providing endpoints for a GTP tunnel and a Mobile IP tunnel.27. The apparatus according to claim 26, further comprising: means forproviding a packet routing function between the GGSN interface and theforeign agent interface.
 28. The apparatus according to claim 23,further comprising: means for coupling an AAA emulation module to theAAA entity via an fifth interface, wherein the AAA emulation moduleprovides an accounting function by interacting with a home network's AAAfor Mobile IP Foreign Agent challenge authentication and 3GPP2 packetdata accounting.
 29. An apparatus that enables communication between ahome CDMA (Code Division Multiple Access) 2000 packet data system and avisited GPRS (General Packet Radio Service) system comprising a SGSN(Serving GPRS Support Node), when a CDMA 2000 packet data nativesubscriber using Simple IP roams to a visited GPRS system, wherein thehome CDMA2000 packet data system comprises a ANSI-41 home locationregister, an AAA entity, and a LNS, comprising: an ANSI-41 visitedlocation register; a GSM home location register; means for coupling theANSI-41 visited location register to the ANSI-41 home location registervia a first interface, wherein the ANSI-41 visited location registerallows a subscriber to register over the first interface; and means forcoupling the GSM home location register to the SGSN via a secondinterface, wherein the GSM home location register allows a subscriber toregister over the second interface.
 30. The apparatus according to claim29, further comprising: means for coupling a LAC (Layer 2 TunnelingProtocol Access Concentrator) emulation module to the LNS (Layer 2Tunneling Protocol Network Server) via an third interface, wherein theLAC emulation module supports bearer connectivity between the visitedand home networks over the third interface; and means for coupling aGGSN emulation module to the SGSN via a fourth interface, wherein theGGSN emulation module supports bearer connectivity between the visitedand home networks over the fourth interface by: means for presenting aGGSN interface to the visited system; and means for presenting a normalrouting interface to the CDMA 2000 packet data system to thereby providea packet routing function between the GGSN interface and the homesystem.
 31. The apparatus according to claim 29, further comprising:means for providing endpoints for a GTP tunnel and an IPSec tunnel. 32.The apparatus according to claim 31, further comprising: means forcoupling an AAA emulation module to the AAA entity via a fifthinterface, wherein the AAA emulation module provides an accountingfunction by: means for interacting with the home network's AAA for L2TPauthentication and 3GPP2 packet data accounting over the fifthinterface.
 33. An apparatus that enables communication between a homeGPRS (General Packet Radio Service) system comprising a GSM homelocation register, a GGSN, and an AAA (Authentication, Authorization,and Accounting) entity; and a visited CDMA 2000 packet data system thatcomprises an ANSI-41 visited location register, an AAA entity, and apacket data serving node/foreign agent, when a GPRS native subscriberusing Mobile IPv4 (Internet Protocol version 4) roams to the visitedCDMA 2000 packet data system, comprising: means for coupling a homeagent emulation module to the packet data serving node/foreign agent viaa first interface, wherein the home agent emulation module presents ahome agent interface to the visited system; and means for coupling aSGSN emulation module to the GGSN via a second interface, wherein theSGSN emulation module presents a SGSN interface to the home system tosupport bearer connectivity between the visited and home networks byproviding a packet routing function between the SGSN interface and thehome agent interface.
 34. The apparatus according to claim 33, furthercomprising: means for providing endpoints for a GTP tunnel and a MobileIP tunnel.
 35. The apparatus according to claim 33, further comprising:means for coupling a ANSI-41 home location register emulation module tothe ANSI-41 visited location register via a third interface; and meansfor coupling a GSM visited location register emulation module to the GSMhome location register via another third interface to allow a subscriberto register.
 36. The apparatus according to claim 35, furthercomprising: means for coupling a AAA emulation module to the AAA entityvia a fourth interface and to the AAA entity via a fifth interface,wherein the AAA emulation module interacts with: the visited network'sAAA for Mobile IP authentication and 3GPP2 packet data accounting, overthe fifth interface, and the home network's AAA for 3GPP packet dataaccounting, over the fourth interface.
 37. An apparatus that enablescommunication between a home GPRS (General Packet Radio Service) systemcomprising a GSM home location register, a GGSN, and an AAA(Authentication, Authorization, and Accounting) entity, and a visitedCDMA 2000 packet data system that comprises an ANSI-41 visited locationregister, an AAA entity, and a packet data serving node/LAC entity, whena GPRS native subscriber using Simple IP roams to the visited CDMA 2000packet data system, comprising: means for coupling a SGSN emulationmodule to the GGSN over a first interface, wherein the SGSN emulationmodule presents a SGSN interface to the home system; and means forcoupling a LNS emulation module to the packet data serving node/LACentity over a second interface, wherein the LNS emulation modulepresents a L2TP Network Server (LNS) interface to the visited system,wherein the interface provides the packet routing function between theSGSN emulation module and the LNS emulation module.
 38. The apparatusaccording to claim 37, wherein bearer connectivity is supported betweenthe visited and home networks by providing a packet routing function.39. The apparatus according to claim 38, further comprising: means forproviding endpoints for a GTP tunnel and a Mobile L2TP tunnel.
 40. Theapparatus according to claim 38, further comprising: means for couplinga ANSI-41 home location register emulation module to the ANSI-41 visitedlocation register via a third interface, wherein the ANSI-41 homelocation register emulation module allows a subscriber to register; andmeans for coupling a GSM visited location register emulation module tothe GSM home location register via another third interface, wherein theGSM visited location register emulation module allows the subscriber toregister.
 41. The apparatus according to claim 40, further comprising:means for coupling an AAA emulation module to the AAA entity via afourth interface and coupled to the AAA entity via a fifth interface,wherein the AAA emulation module interacts with: the visited network'sAAA entity, over an fifth interface, for L2TP authentication and 3GPP2packet data accounting, and the home network's AAA entity, over an sixthinterface, for 3GPP packet data accounting.